51671821 has 2 divisors, whose sum is σ = 51671822. Its totient is φ = 51671820.

The previous prime is 51671801. The next prime is 51671827. The reversal of 51671821 is 12817615.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 32046921 + 19624900 = 5661^2 + 4430^2 .

It is a cyclic number.

It is not a de Polignac number, because 51671821 - 2⁹ = 51671309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51671827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25835910 + 25835911.

It is an arithmetic number, because the mean of its divisors is an integer number (25835911).

Almost surely, 2^51671821 is an apocalyptic number.

It is an amenable number.

51671821 is a deficient number, since it is larger than the sum of its proper divisors (1).

51671821 is an equidigital number, since it uses as much as digits as its factorization.

51671821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3360, while the sum is 31.

The square root of 51671821 is about 7188.3114150682. The cubic root of 51671821 is about 372.4642453257.

The spelling of 51671821 in words is "fifty-one million, six hundred seventy-one thousand, eight hundred twenty-one".